[Snyk] Upgrade postcss from 8.2.4 to 8.4.5

Snyk has created this PR to upgrade postcss from 8.2.4 to 8.4.5.

merge advice As this is a private repository, Snyk-bot does not have access. Therefore, this PR has been created automatically, but appears to have been created by a real user.
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:information_source: Keep your dependencies up-to-date. This makes it easier to fix existing vulnerabilities and to more quickly identify and fix newly disclosed vulnerabilities when they affect your project.

The recommended version is 29 versions ahead of your current version.
The recommended version was released 2 months ago, on 2021-12-13.

The recommended version fixes:

Severity	Issue	PriorityScore (*)	Exploit Maturity
	Information Exposure SNYK-JS-NANOID-2332193	307/1000 Why? Proof of Concept exploit, CVSS 4	Proof of Concept

(*) Note that the real score may have changed since the PR was raised.

Release notes

Package name: postcss

8.4.5 - 2021-12-13
- Fixed raws types to make object extendable (by @ 43081j).
- Moved from Yarn 1 to pnpm.
8.4.4 - 2021-11-27
- Fixed absolute path in source map on zero plugins mode.
8.4.3 - 2021-11-26
- Fixed this.css.replace is not a function error.
8.4.2 - 2021-11-26
- Fixed previous source map support in zero plugins mode.
8.4.1 - 2021-11-24
- Fixed Stringifier types (by @ 43081j).
8.4.0 - 2021-11-24

PostCSS 8.4 brought ranges for warnings and errors, smaller node_modules size, lazy parsing to avoid PostCSS does nothing warning, and TypeScript fixes.

Thanks to Sponsors

This release was possible thanks to our community.

If your company wants to support the sustainability of front-end infrastructure or wants to give some love to PostCSS, you can join our supporters by:
- Tidelift with a Spotify-like subscription model supporting all projects from your lock file.
- Direct donations in PostCSS & Autoprefixer Open Collective.
Rages for Errors and Warnings

@ adalinesimonian, the author of amazing Stylelint extension for VS Code, added ranges to errors and warnings.
```
result.warn(msg, { index })           // One character warning at index
result.warn(msg, { endIndex })        // Starts at node start, ends at endIndex
result.warn(msg, { index, endIndex }) // Starts at index, ends at endIndex
result.warn(msg, { start })           // Starts at start, ends at node end
result.warn(msg, { end })             // Starts at node start, ends at end
result.warn(msg, { start, end })      // Starts at start, ends at end
result.warn(msg, { word })            // Starts at word location, ends at word index + length
```
It will improve DX in the IDE extension.

Lazy Parsing

Previously, we found that many tools run PostCSS even if the developer didn’t pass any PostCSS plugins. Parsing is the most expensive step in CSS processing. It led to a waste of resources without any reason.

We tried to resolve the problem by adding a PostCSS does nothing warning. But it didn’t force tool authors to be more careful with user’s resources.

If PostCSS sees that tool call it without passing plugins (or changing parser/stringifier), PostCSS will not parse CSS (until toll will call Result#root). In 8.4, @ bogdan0083 (with the help of @ WilhelmYakunin) tries to solve the problem in another way. It allows us to save resources and remove the PostCSS does nothing warning.
```
// No plugins, we do not parse CSS
let result = await postcss().process(css, { from  })
result.css  // Is the same string passed to process()
result.map  // Special 1-to-1 source map
result.root // CSS will parsed only here
```
Install Size Reduction

With ≈60M weekly downloads, PostCSS has responsibility for the world’s resource spending.

Together with @ 7rulnik we reduced source-map-js size. It is transitive dependency of PostCSS.

In 8.4, we moved to a fixed version of source-map-js, which reduced the postcss size in your node_modules from ≈1 MB to 0.3 MB. With the huge popularity of PostCSS, it will free a lot of resources on our CIs.

Migration from Jest to uvu

@ kimoofey refactored all tests from the popular Jest framework to small and fast uvu.

It will not affect end-users. However, it reduced our node_modules size by 33 MB and made tests twice faster (yarn install & yarn unit: 24 → 13 seconds).

TypeScript Fixes
- Added Processor types.
- Added Stringifier types (by @ 43081j).
- Fixed types Root and Document in result values (by @ 43081j).
- Fixed Node#walkRules() types (by @ hudochenkov).
Other Changes
- Fixed docs (by @ paulshryock).
8.3.11 - 2021-10-21
8.3.11
8.3.10 - 2021-10-20
- Fixed Maximum call stack issue of some source maps (by @ yetingli).
8.3.9 - 2021-10-04
- Replaced nanocolors to picocolors.
- Reduced package size.
8.3.8 - 2021-09-25
8.3.7 - 2021-09-22
8.3.6 - 2021-07-21
8.3.5 - 2021-06-17
8.3.4 - 2021-06-14
8.3.3 - 2021-06-14
8.3.2 - 2021-06-11
8.3.1 - 2021-06-09
8.3.0 - 2021-05-21
8.2.15 - 2021-05-10
8.2.14 - 2021-05-05
8.2.13 - 2021-04-26
8.2.12 - 2021-04-22
8.2.11 - 2021-04-22
8.2.10 - 2021-04-11
8.2.9 - 2021-03-30
8.2.8 - 2021-03-09
8.2.7 - 2021-03-03
8.2.6 - 2021-02-10
8.2.5 - 2021-02-06
8.2.4 - 2021-01-09